“North Korea has produced material for many more nuclear weapons,” said Hans Kristensen, who heads that FAS's nuclear information project. “The high-end of the estimates range from [enough material for] 30 to 60.”

As far as we know, none of North Korea's weapons are actually deployed for use yet.

By contrast, the United States has missile technology that can carry 10 warheads at once (it's called MIRV, and its use is limited by treaty to less than 10 missiles) and send them to ten different targets in a single shot.

US President Donald Trump leaves the CIA headquarters after speaking to 300 people on January 21 2017 in Langley, Virginia . Trump spoke with about 300 people in his first official visit with a government agency. (Photo: Olivier Doulier/Getty Images)

This picture taken on September 3, 2017 and released by North Korea's official Korean Central News Agency (KCNA) on September 4, 2017 shows North Korean leader Kim Jong-Un attending a meeting with a committee of the Workers' Party of Korea about the test of a hydrogen bomb, at an unknown location. North Korea said it detonated a hydrogen bomb designed for a long-range missile on September 3 and called its sixth and most powerful nuclear test a "perfect success", sparking world condemnation and promises of tougher US sanctions. / AFP PHOTO / KCNA VIA KNS / STR / South Korea OUT / REPUBLIC OF KOREA OUT ---EDITORS NOTE--- RESTRICTED TO EDITORIAL USE - MANDATORY CREDIT "AFP PHOTO/KCNA VIA KNS" - NO MARKETING NO ADVERTISING CAMPAIGNS - DISTRIBUTED AS A SERVICE TO CLIENTS THIS PICTURE WAS MADE AVAILABLE BY A THIRD PARTY. AFP CAN NOT INDEPENDENTLY VERIFY THE AUTHENTICITY, LOCATION, DATE AND CONTENT OF THIS IMAGE. THIS PHOTO IS DISTRIBUTED EXACTLY AS RECEIVED BY AFP. / (Photo credit should read STR/AFP/Getty Images)

The U.S. has a total estimated inventory of about 6,600 weapons - second only to Russia. 1,800 or so are deployed and ready to use.

Experts are a little puzzled by the president's tweet because North Korea already knows it's outgunned here.

“The fact even that they're developing nuclear weapons to have precisely that type of capability shows that they're fully aware of what's pointed at them,” Kristensen said.

The “football” is the nickname for a briefcase of materials needed to order a nuclear strike, carried by an armed military officer wherever the president goes.

Inside are a variety of attack scenarios and targets, along with a little-laminated card called the “biscuit.”

It's a card with secret codes to confirm the president is the one giving the order to strike.

That code goes to the Pentagon and strategic command, which then blasts a short encrypted message to nuclear submarines, bombers, and/or missile silos… containing yet more codes to unlock the weapons for firing.

While the world's power players try to make sense of the strategy, and whether there is one, behind the president's tweets — the message Trump aimed to convey about American nuclear prowess is both true and already known to leaders around the world.